1. Field of the Invention
The present invention relates to a pH adjusting apparatus and a method of adjusting the pH of a fluid using the same. More particularly, the present invention relates to a pH adjusting apparatus for adjusting the pH of a solution accurately and easily, and a method of adjusting the pH of a solution using the pH adjusting apparatus.
2. Description of the Related Art
Generally, molecular diagnosis of specific pathogenic species consists of four steps: cell lysis, DNA separation, DNA amplification, and DNA detection.
Efficient extraction of DNAs from cells is needed for many applications and essential for molecular diagnosis, in particular, isolation and quantification of pathogenic species. Generally, molecular diagnosis involves DNA amplification after DNA extraction. Examples of DNA amplification are polymerase chain reaction (“PCR”) amplification, ligase chain reaction (“LCR”) amplification, stranded-displacement amplification, nucleic acid-based amplification, repair chain reaction (“RCR”) amplification, helicase-dependent amplification, Qβ replicase amplification, or ligation activated transcription (“LAT”) amplification.
DNA separation from cells is performed using a material capable of binding with DNA. A material that can be used for DNA separation may be silica, glass fiber, an anion exchange resin, or a magnetic bead. Generally, cell lysis can be performed using a mechanical method, a chemical method, a thermal method, an electrical method, an ultrasonic method, or a microwave method.
In various biological assays including molecular diagnosis of specific pathogenic species, individual steps may be performed at different pH values.
Conventionally, pH adjustment in biological assays is achieved by adding or removing a pH-adjusting solution, e.g., an acidic solution, a basic solution, a neutral solution, or a buffer solution, to or from a sample solution. However, the addition or removal of the pH-adjusting solution requires a separate apparatus and process and causes the dilution of the sample solution.
Such an additional process and apparatus for the addition or removal of the pH-adjusting solution may seriously affect micro-volume biological sample assays, and the dilution of the sample solution may adversely affect acquisition or amplification of desired samples. Furthermore, the added pH-adjusting solution may act as an inhibitor in subsequent biological assays. In this case, it is necessary to remove the pH-adjusting solution after use.
In biological assays, an electrolysis method is used as another method for adjusting the pH of a solution. For example, the pH of a solution can be adjusted using H+ and OH− ions respectively generated from an anode and a cathode by electrolysis of water. In the pH adjustment method using electrolysis, a current difference may be caused by a salt or cell concentration variation between samples or a resistance change due to gas generation. Thus, in the electrolysis method, it is important to constantly maintain a current, since current is the major factor for pH adjustment.
However, a pH adjusting apparatus using constant current electrolysis has not yet been reported. Furthermore, the use of a constant current-generating condenser increases the size and weight of a pH adjusting apparatus, thereby making it difficult to make the apparatus portable.